Mr. al-Mahmoudi’s extradition to Libya puts him at risk of being tortured or executed without trial, the human rights group Amnesty International said Monday.

The case sparked tension between Tunisian Prime Minister Hamadi Jebali, who approved Mr. al-Mahmoudi’s extradition, and President Moncef Marzouki, who had opposed it out of concern for the Libyan’s safety.

Mr. Jebali is from the moderate Islamist Ennahda party. Mr. Marzouki, a former human rights activist, belongs to the liberal Congress for the Republic.

Amnesty International condemned authorities in Tunis for handing Mr. al-Mahmoudi over to Libyan officials.

“While all perpetrators of human rights violations must be brought to justice, by extraditing al-Baghdadi al-Mahmoudi, Tunisian authorities have not only violated their own law but also their international obligation not to return anyone to a country where they are at risk of human rights violations,” said Hassiba Hadj Sahraoui, Amnesty International’s deputy director for the Middle East and North Africa.

Amnesty International has documented numerous cases in Libya in which detainees signed confessions after being tortured. It also has evidence of at least 20 cases of deaths in custody in Libya since August.

Gadhafi and one of his sons, Mutassim Gadhafi, were killed in the custody of Libyan rebel militias in October.